Piston cup



March 24, 1953 v E. H. SMITH 2,632,680

PISTON CUP Filed Dec. 10, 1949 INVENTOR. EDMUND l1. -S/7/7 Patented Mar.24, 1953 UNITED STATES PATENT OFFICE PISTON CUP Edmund H. Smith,Palmyra, N. Y., assignor to .The Garlock Packing Company, Palmyra, N.Y., a corporation of New York I Application December 10, 1949, SerialNo. 132,373

. 2 Claims. (01. 30933) 1 2 This invention relates to improvements 1njectionable condition which can lead to serious piston cups, and moreparticularly to P leakage past the piston.

cups which are formed of suitable molded ma- An important object of thpresent invention terial with means incorporated therein for reis theprovision of a piston sealing cup in which inforcing the cup. 5 fabricis employed for reinforcing purposes in In providing reinforcing meansin such piston such an arrangement that the sealing flang of psheretofore pr uc d, the cup has commonly the cup is uniformly andadequately reinforced been formed from a flat blank of sheet fabricaround its entire circumference. material impregnated with suitablerelatively Another object of this invention is the prosoft, flexibleplastic material. Such a blank vision of a piston sealing cup withrelatively commonly has included plural plies of the fabric rigid baseportions which, together with such a so arranged that its threads runonly in two uniformly reinforced sealing flange, give aderight-angulardirections. When molded in suitquate support to said flange against theforce ably shaped dies, such a blank is converted from of pressure fluidexerted axially upon the sealits flat shape to the desired cup shapewith a 5 ing flange.

cylindrical sealing flange for effecting a seal be- The foregoing andother objects are accomtween a piston and a wall of a cylinder in whichplished according to the present invention, in the piston operates. itsbroader aspects, by forming the cylindrical Such piston cups, in actualservice, have been sealing flange of a piston cup, principally fromunsatisfactory, either because they break down 29 a cylindrical blankrather than from a flat in service or permit serious leakage past thepisblank. Such a cylindrical blank preferably inton after a relativelyshort period of service. cludes plural layers of fabric wound in cylin-Hence, frequent replacements of such piston drical form with the warpand weft threads of cups have been necessary with resultant expense thefabric extending on the bias relatively to not only in the cost of thereplacement cups, but the axis of the blank, the multi-ply fabric beinalso arising from the fact that the machine in impregnated by andembedded within the moldwhich the cup is employed is necessarily outable material of which the sealing flange isito O Service frequently W enew ups are being be formed. Such a cylindrical blank of suitinstalled.able axial length is molded in suitably shaped The principal reason forthe mentioned short- 30 dies, in association with mounting portions ofcomings of such prior piston cups, apparently a piston cup which, forexample, may b inthe resides in the fact that, when formed from suchform of a rigid shallow cu with a flat filler blanks, the sealing flangeof the cup has altermolded therewithin. nate relatively rigid portionsand flexible por- Although the present invention may be emtions about.lts circumference corresponding to bodied in a variety of forms ofpistoncups alternate portions in which the threads of the which may beformed in various ways, neverfabricextend both parallel and rightangularly theless, for illustrative purposes, a preferred to the freeedge of the sealing flange at four form of piston cup is illustrated inthe accomuniformly spaced circumferential points and panying drawing,together with preferred means other, intermediate portions wherein thefabric for making such a cup, In the said drawing:

threads extend at oblique angles to the free edge Figure 1 is a centralaxial section of a p of the sealing flange. In service, such cups ferredform of piston cup according to this inwear excessively at the flexibleportions, probvention.

ably because of the inability of the cup to main- Fig. 2 is aperspective view, partly broken tain unifo engagement With e y e awayand diagrammatic in certain respects, around the entire circumference ofthe cup. showing the manner in which a plurality of 03- In' such priorcups, also, it sometimes happens lindrical sealing flange blanks may becut from that the threads which extend perpendicular to a cylinder ofmulti-ply fabric material to form the free edge of the sealin flange.become seindividual blanks, each useful for forming a cy- "verelystrained during molding and break then lindrical flange of apiston cup.

ornsoon a t r t p s lac d in service, thus Fig. 3 is a side eleva'tionalview of one of the materially weakening the cup and greatly shortsealingflange blanks as it would appear if out .ening its lifex Also, thisweakening of the fabric open axiau at one circumferential point andtends. to break down the Weave of the fabric, the flattened out,ile'adingto loose threads or .hangnails; an 010- Fig. 4 is a perspectiveview of an individual cylindrical blank of multi-ply material suitablefor use in forming a piston cup according to this invention.

Referring to the drawings with more particularity, a piston sealing cupaccording to this invention may be as shown in Fig. 1 and may include arelatively rigid mounting cup II, a resilient, approximately cylindricalsealing element I 2, suitably bonded at one end marginal portion thereofto the inner face of a peripheral flange l3 of said mounting cup, and adisc-like filler piece l4 suitably bonded to the inner face of thebottom l5 of said mounting cup.

The mounting cup H is preferably formed of sheet metal, although itmaybe of some other suitably strong and relatively rigid material. Itsflange I3 preferably encircles and supports an inner end portion l6 ofthe sealing element. Although said flange may exert some sealing effectwith respect to a related cylinder wall, its primary purposes are tosupport the flexible sealing, element and to maintain or aid inmaintainingsubsta-ntia-l concentricity of the piston relatively to acylinder'within which it operates.

The filler piece it serves to back up the inner .end portion [6 of thesealing element to restrain 'the material insaid portion fromflowingradially inwardly in the mounting cup in response to fluid pressureexerted axially upon the free end of the-sealing element duringoperation. 'The'filler piece also may function as a gasket to effect afluid-tight seal around an opening i'l formed in said filler piece andin the bottom I5 of the monnting'cup to receive a mounting rod or boltand nut assembly (not shown) by which the piston cup may be mounted upona piston body when placed inservice. The filler piece may be of anysuitable material such as hard or soft rubber, or metal or reinforcedimpregnated fabric or any other material having characteristics adaptingit to perform one or both of its mentioned functions.

The sealing element i2 is preferably formed of reinforced, moldedmaterial", such as neoprene or other molded material suitable forwithstanding pressure strains to which it may be subjected in use andforresisting deleterious effects of the fluid with which the piston is tofunction. Prior to installation of the piston cup within a cylinder, inwhich it is to operate, the flexible sealing-element f2, preferably,flares out w-ardly toward its free edge, but is deformed somewhat to amore nearly cylindrical shape when installed within the said cylinder.The sealing element 12, accordingto the present invention, includes aplurality of embedded, circumferentially-extending plies I 8 of fabricin all of which the warp and weft threads, at all circumferentialpoints, extend angul'arly with respect to lines which are coincidentwith the said sealingelement and parallel to the axis of the piston cup;and for convenience such disposition of such threads is sometimes hereinreferred to by language including the word bias. It is preferred thatthe warp threads and the weft threads be arranged in similar, butopposed angularity with respect to the mentioned parallel lines;however, the use of the word bias, while inclusive ofsuch similarity ofangularity, is not to be taken as limited to a structure in which suchsimilarity of angularity is necessarilypres- ;ent. The mentioned biasarrangement is indicated' in broken lines in Figs. 1 and 3, only a lim-.ited number of threads being thus indicated.

The sealing element It is formed with a free or outer end portion [9extending axially beyond the flange N3 of the mounting cup. This outerend portion, in accordance with more or less conventional practice, mayhave an annular end surface 20 which is tapered to a relatively sharpcircumferential edge 2! at the outer periphery of the piston cup.

Piston cups as illustrated and described herein may be manufacturedeconomically by a novel method which may be understood from thefollowing description which, in turn, may aid in affording a completeunderstanding of the structure of thepiston cup itself.

According to a preferred manner of making such piston cups, suitablewoven fabric, preferably in a relatively large sheet, is impregnatedwith.:moldable material which when formed and cured. will be suitablefor resisting pressure and also for resisting the deleterious action ofthe fluid or fluids with which the piston is to function. Neoprene orother resilient rubber-like substances have been found to be suitablefor use as such moldable material. The impregnated fabric sheet is woundon the bias upon a mandrel 25?, of circular cross-section, in pluralplies until the wound fabric forms a cylinder 127' of about thethickness and cross-sectionalsize of a desired blank, from which amolded sealing element i2 may be formed.

The mentioned impregnation of the fabric can be. deferred after it hasbeen wound in cylindrical form, or if the fabric has been impregnated insheet form as hereinbefore described, it may be supplementallyimpregnated, if desired, after being formed into a cylinder.

After winding. of the impregnated fabric to the extent indicated, anyremaining: unwound fabric is severed and laid aside. Then the fabriccylinder 21 'iscut transversely into: plural annular blanks 29. Thismaybe accomplished conveniently by supporting plural knives 3dasdiagrammatically illustrated in Fig. 2., at various spaced positionsalong said fabric cylinder and at similar angles such as will enable theknives to cut transversely through the fabric cylinder and to taper theends of each blank to conform it somewhat to the ultimate desiredcross-sectional configuration of a sealing element l2.

The mandrel 25 with the fabric cylinder 21 thereon is rotated about-itsaxis while the knives '31? are moved inwardly in unison toward themandrel in a general direction which is parallel to the longitudinal,axis of the knives; When these: cuts have been completed, the knives arewithdrawn, leaving plural blanks in the form of impregnated fabric rings29 which are then removed from the mandrel. The ring blanks 2'9, asithusproduced, have tapered opposite end surfaces 29a, 29b and the warp andweft threads of the fabric in said blanks are on the bias. One of therings 29 is illustrated in Fig. 3 as though it were cut longitudinallyat one circumferential point and then rolled out as a flat strip. Thisillustration is included in the drawing only to indicate clearly, inbroken lines, the fact that the warp and weft threads of all plies of'the fabric l8 are on the bias. The bias arrange ment of the threads ofthe fabric is also indi- 'cated in broken lines in Fig. 1.

Afterformation of a ring blank '29, it is associated with a mounting cupII and a flat blank which, in the finished piston cup, will be thefiller piece I4; these mentioned parts being associated within suitablyshaped molds in their approximate positions. as. indicated in Fig, I.'In

associating these parts in the mold, various adjacent portions thereofpreferably are suitably treated, either by application thereto ofadhesive material or otherwise to enhance the ultimate bond of thoseparts to each other.

After the mentioned parts are assembled in the molds, or in one of twocooperating molds, the molds are brought together to closed positionsand subjected to heat and pressure in a well understood manner to pressthe several parts to their final desired shapes as they appear in Fig. 1and to cure all such parts which are of curable material. Thereafter,the finished piston cup is removed from the molds.

It should be apparent that the hereinbeforedescribed method ofmanufacturing piston cups is well suited for producing piston cups ofthe general character shown in the drawings. It should be apparent alsothat piston cups as illustrated and described herein constitute asubstantial improvement over prior piston cups because of the fact thatthe fabric of which the sealing element I2 is constructed is arranged sothat the warp and weft threads are on the bias at each and everycircumferential point about the piston cup.

Because of the mentioned bias arrangement, the sealing element engagesan adjacent cylinder wall uniformly at all points therearound, therebyyielding an improved uniform sealing effect, and consequently minimizingleakage of fluid past the piston.

It should also be apparent that in piston cups of the characterdescribedherein the bias arranged threads are under no strain whateverduring the molding operation as is the case where fabric reinforcedpiston cups are formed from fiat blanks. Because of this absence ofstrain, the threads in the fabric remain fully intact in their originalinterwoven condition and,

therefore, cannot become loose or become separated either in whole or inpart from the sealing element. In prior structures, threads often becamethus separated and caused considerable trouble in operation. Suchtrouble is completely obviated in devices according to this invention.

It should be obvious also that while the use of plural knives isdesirable it is not essential and the process disclosed herein may bepracticed with the use of only a single knife. Also while the describedangular positioning of a knife with respect to the mandrel is desirable,nevertheless, if desired a knife may be disposed perpendicularly to themandrel or at a greater or lesser angle with respect thereto. When thering 29 is cut with its opposite ends tapered as hereinbefore described,the blank will, of course, conform more accurately to the ultimate shapeof the sealing element 12, but if the end surfaces 29a and 291) are nottapered the proper tapering of the end surface 20 of the sealing elementcan be accomplished by the use of dies which are shaped to yield such ataper. Although the sealing element I2 and the blank 29 from which it isformed have been hereinbefore described as having layers of fabricextending substantially throughout the entire thickness, nevertheless.it should be understood that plural plies of fabric could be providedwhich would occupy less than the entire thickness of the sealingelement. For example, the plies could be disposed only in the center ofthe section of said sealing element with moldable material of anappreciable thickness constituting both the outer face and the innerface of said element, or the plies could be concentrated at the inner orouter face of the element, or for some purposes they could beconcentrated at its inner and outer faces with an appreciable thicknessof molded material in the center of the section of the sealing element.In all these possible arrangements it should be obvious that thedescribed bias disposition of the threads will yield a highly beneficialresult.

Although an attempt has been made to particularly point out severalpossible variations of this invention, it is not intended, by so doing,to limit the possible variations to those described; for the presentinvention obviously may be practiced in various other ways and invarious other structures without, however, departing from the inventiveconcept as set forth in the following claims.

What I claim is:

1. A piston cup comprising a rigid mounting cup, having an approximatelycylindrical peripheral flange, a flexible sealing element consistingsolely of an approximately cylindrical flexible sealing sleeve includingplural circumferentially extending layers of fabric molded therewithwith the threads of the fabric on the bias at all circumferential pointsaround said element, one end of said sleeve being confined within saidperipheral flange, and means within the cup for restraining the said oneend of said sleeve against radially inward deformation.

2. A piston cup according to claim 1, further characterized in that thesaid restraining means comprise a circular filler piece, overlying theinner face of the bottom of said cup with the outer peripheral surfaceof said filler piece in engagement with a cylindrical surface of aninner marginal portion of said one end of the flexible sealing sleeve torestrain the latter against radially inward displacement.

EDMUND H. SMITH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 612,687 Bosch Oct. 18, 18981,320,675 Christenson Nov. 4, 1919 1,845,939 Snowden Feb. 16, 19321,945,524 Foehr Feb. 6, 1934 2,264,741 Chamberlain Dec. 2, 19412,318,757 Christenson May 11, 1943 2,388,520 Bowie Nov. 6, 19452,400,533 Buifington May 21, 1946 2,448,114 Olson Aug. 31, 19482,454,074 Marc Nov. 16, 1948

